code: def func(x):
      return (
          np.sin(x * 3 * 3.14)
          + 0.3 * np.cos(x * 9 * 3.14)
          + 0.5 * np.sin(x * 7 * 3.14)
      )
  
file_path: GPflow/notebooks/advanced/gps_for_big_data.pct.py
imports: import itertools
  import time
  import matplotlib.pyplot
  import numpy
  import tensorflow
  import gpflow
  from gpflow.ci_utils import reduce_in_tests
label_desc: Use image node_id 1 for calling a global function with example usage: func(x) and returns: unknown